Apple iMac 27"" - 1TB Fusion - Intel Core i5

Yes, unlike the 21.5-inch models, the 27-inch iMac (Mid 2017) has user-accessible RAM slots. You can upgrade the RAM by opening a small door on the back of the display. It uses 2400MHz DDR4 SO-DIMMs. Always refer to Apple's support documentation or consult a professional for exact specifications and installation instructions.

A Fusion Drive combines a small, fast solid-state drive (SSD) with a larger, traditional hard disk drive (HDD). macOS automatically manages files, placing frequently accessed items on the SSD for faster performance, and less used items on the HDD for storage capacity. This provides a balance between speed and storage at a lower cost than a pure SSD.

The iMac (Mid 2017) originally shipped with macOS Sierra. It supports subsequent macOS versions, including macOS Monterey (12). For the latest compatibility, always check Apple's official macOS compatibility list. Info needed: [Max supported macOS version]

Yes, the iMac (Mid 2017) includes two Thunderbolt 3 (USB-C) ports, which can be used to connect external displays. You can connect up to two 4K displays (4096x2304 @ 60Hz) or one 5K display (5120x2880 @ 60Hz) in addition to the built-in 5K display.

To perform a factory reset, you'll need to erase the internal drive and reinstall macOS. You can do this by booting into macOS Recovery (hold `Command + R` during startup), using `Disk Utility` to erase the drive, and then selecting 'Reinstall macOS' from the Utilities window.

For casual or amateur video editing of HD footage, this iMac can perform well, especially with its 5K display for viewing. However, for professional 4K video editing, heavy effects, or long projects, the 8GB RAM and Intel Core i5 processor may lead to longer render times and slower performance. Upgrading the RAM is highly recommended for such tasks.

Close unnecessary applications, check `Activity Monitor` (Applications > Utilities) for resource-intensive processes, and ensure your macOS is updated. Restarting the iMac can often resolve temporary performance issues. Clear browser caches and manage startup items.

Check your display settings in `System Settings` > `Displays`. If an external display is connected, ensure the cable is secure. Restarting the iMac can sometimes fix display glitches. If the issue persists, contact Apple Support.

Toggle Wi-Fi/Bluetooth off and on in the `Control Center` or `System Settings`. Restart your router and modem. If the problem persists, try resetting network settings (found under `System Settings` > `Network` by removing and re-adding your Wi-Fi service).

Ensure they are charged and powered on. For wired devices, try connecting them to a different USB port. For Bluetooth devices, try re-pairing them via `System Settings` > `Bluetooth`.

Ensure the power cable is securely plugged into both the iMac and a working power outlet. Try a different power outlet. If the screen remains black, try resetting the SMC (System Management Controller) by unplugging the power cord for 15 seconds, then plugging it back in and waiting 5 seconds before pressing the power button.